1. Field of the Invention
The present invention relates to a stator which is used in a rotating electrical machine such as an electric motor or an electric generator.
This application is based on Japanese Patent Application No. 2003-288078, filed Aug. 6, 2003, the contents of which are incorporated herein by reference.
2. Background Art
As the winding of a stator in a rotational electrical machine, there are known, per se, a winding which is made using a so called round wire whose cross section is approximately circular, and a winding which is made using a so called rectangular wire whose cross section is approximately rectangular.
Since gaps occur between the turns of a round wire even if they are wound very tightly and closely, the resulting space factor is inevitably rather low; but, by contrast, with a rectangular wire, there is the advantage that, by appropriately lining up the coils side by side, it is possible to attain a high space factor without the occurrence of any substantial gaps. Here by “space factor” is meant the ratio of the coil wire occupation area to the slot cross sectional area; as is per se well known, it is possible to anticipate enhancement of the performance of a rotational electrical machine by increasing the space factor.
In this connection, since the space factor is reduced if a winding fault occurs when winding such a rectangular wire upon an insulating bobbin, which is undesirable, accordingly it is necessary to wind the rectangular wire upon the bobbin without the occurrence of faults.
As a prior art technique for preventing the occurrence of such winding faults, there are known, for example, the technique described in Patent Document 1 (Japanese Patent Laying Open Publication 2000-245092), and the like. With this technique disclosed in Patent Document 1, by lining up the insulating bobbin or the like while shaping the form of the rectangular wire with a special type of shaping device, it is ensured that no winding faults are engendered while performing the winding.
However, in the case of this prior art technique, there is the problem that the manufacturing cost is increased, because it is necessary to perform special form shaping for the rectangular wire as a pre-processing stage before actually winding up the rectangular wire upon the bobbin, and this requires a great deal of man-hours.
Furthermore, there is the problem that the construction of the winding machine for doing this job becomes rather complicated, so that the cost of the equipment is increased, since a shaping device is required for performing this special form shaping upon the rectangular wire.
Thus the objective of the present invention is, by merely adding a simple constructional feature to the insulating bobbin, to provide a stator with which it is possible to prevent the occurrence of winding faults when winding the rectangular wire.